prompt.py

"""Functions for prompting the user for project info."""
import functools
import json
from collections import OrderedDict

import click
from jinja2.exceptions import UndefinedError

from cookiecutter.environment import StrictEnvironment
from cookiecutter.exceptions import UndefinedVariableInTemplate


def read_user_variable(var_name, default_value):
    """Prompt user for variable and return the entered value or given default.

    :param str var_name: Variable of the context to query the user
    :param default_value: Value that will be returned if no input happens
    """
    return click.prompt(var_name, default=default_value)


def read_user_yes_no(question, default_value):
    """Prompt the user to reply with 'yes' or 'no' (or equivalent values).

    - These input values will be converted to ``True``:
      "1", "true", "t", "yes", "y", "on"
    - These input values will be converted to ``False``:
      "0", "false", "f", "no", "n", "off"

    Actual parsing done by :func:`click.prompt`; Check this function codebase change in
    case of unexpected behaviour.

    :param str question: Question to the user
    :param default_value: Value that will be returned if no input happens
    """
    return click.prompt(question, default=default_value, type=click.BOOL)


def read_repo_password(question):
    """Prompt the user to enter a password.

    :param str question: Question to the user
    """
    return click.prompt(question, hide_input=True)


def read_user_choice(var_name, options):
    """Prompt the user to choose from several options for the given variable.

    The first item will be returned if no input happens.

    :param str var_name: Variable as specified in the context
    :param list options: Sequence of options that are available to select from
    :return: Exactly one item of ``options`` that has been chosen by the user
    """
    if not isinstance(options, list):
        raise TypeError

    if not options:
        raise ValueError

    choice_map = OrderedDict((f'{i}', value) for i, value in enumerate(options, 1))
    choices = choice_map.keys()
    default = '1'

    choice_lines = ['{} - {}'.format(*c) for c in choice_map.items()]
    prompt = '\n'.join(
        (
            f"Select {var_name}:",
            "\n".join(choice_lines),
            f"Choose from {', '.join(choices)}",
        )
    )

    user_choice = click.prompt(
        prompt, type=click.Choice(choices), default=default, show_choices=False
    )
    return choice_map[user_choice]


DEFAULT_DISPLAY = 'default'


def process_json(user_value, default_value=None):
    """Load user-supplied value as a JSON dict.

    :param str user_value: User-supplied value to load as a JSON dict
    """
    if user_value == DEFAULT_DISPLAY:
        # Return the given default w/o any processing
        return default_value

    try:
        user_dict = json.loads(user_value, object_pairs_hook=OrderedDict)
    except Exception as error:
        # Leave it up to click to ask the user again
        raise click.UsageError('Unable to decode to JSON.') from error

    if not isinstance(user_dict, dict):
        # Leave it up to click to ask the user again
        raise click.UsageError('Requires JSON dict.')

    return user_dict


def read_user_dict(var_name, default_value):
    """Prompt the user to provide a dictionary of data.

    :param str var_name: Variable as specified in the context
    :param default_value: Value that will be returned if no input is provided
    :return: A Python dictionary to use in the context.
    """
    if not isinstance(default_value, dict):
        raise TypeError

    user_value = click.prompt(
        var_name,
        default=DEFAULT_DISPLAY,
        type=click.STRING,
        value_proc=functools.partial(process_json, default_value=default_value),
    )

    if click.__version__.startswith("7.") and user_value == DEFAULT_DISPLAY:
        # click 7.x does not invoke value_proc on the default value.
        return default_value  # pragma: no cover
    return user_value


def render_variable(env, raw, cookiecutter_dict):
    """Render the next variable to be displayed in the user prompt.

    Inside the prompting taken from the cookiecutter.json file, this renders
    the next variable. For example, if a project_name is "Peanut Butter
    Cookie", the repo_name could be be rendered with:

        `{{ cookiecutter.project_name.replace(" ", "_") }}`.

    This is then presented to the user as the default.

    :param Environment env: A Jinja2 Environment object.
    :param raw: The next value to be prompted for by the user.
    :param dict cookiecutter_dict: The current context as it's gradually
        being populated with variables.
    :return: The rendered value for the default variable.
    """
    if raw is None or isinstance(raw, bool):
        return raw
    elif isinstance(raw, dict):
        return {
            render_variable(env, k, cookiecutter_dict): render_variable(
                env, v, cookiecutter_dict
            )
            for k, v in raw.items()
        }
    elif isinstance(raw, list):
        return [render_variable(env, v, cookiecutter_dict) for v in raw]
    elif not isinstance(raw, str):
        raw = str(raw)

    template = env.from_string(raw)

    return template.render(cookiecutter=cookiecutter_dict)


def prompt_choice_for_config(cookiecutter_dict, env, key, options, no_input):
    """Prompt user with a set of options to choose from.

    :param no_input: Do not prompt for user input and return the first available option.
    """
    rendered_options = [render_variable(env, raw, cookiecutter_dict) for raw in options]
    if no_input:
        return rendered_options[0]
    return read_user_choice(key, rendered_options)


def prompt_for_config(context, no_input=False):
    """Prompt user to enter a new config.

    :param dict context: Source for field names and sample values.
    :param no_input: Do not prompt for user input and use only values from context.
    """
    cookiecutter_dict = OrderedDict([])
    env = StrictEnvironment(context=context)

    # First pass: Handle simple and raw variables, plus choices.
    # These must be done first because the dictionaries keys and
    # values might refer to them.
    for key, raw in context['cookiecutter'].items():
        if key.startswith('_') and not key.startswith('__'):
            cookiecutter_dict[key] = raw
            continue
        elif key.startswith('__'):
            cookiecutter_dict[key] = render_variable(env, raw, cookiecutter_dict)
            continue

        try:
            if isinstance(raw, list):
                # We are dealing with a choice variable
                val = prompt_choice_for_config(
                    cookiecutter_dict, env, key, raw, no_input
                )
                cookiecutter_dict[key] = val
            elif isinstance(raw, bool):
                # We are dealing with a boolean variable
                if no_input:
                    cookiecutter_dict[key] = render_variable(
                        env, raw, cookiecutter_dict
                    )
                else:
                    cookiecutter_dict[key] = read_user_yes_no(key, raw)
            elif not isinstance(raw, dict):
                # We are dealing with a regular variable
                val = render_variable(env, raw, cookiecutter_dict)

                if not no_input:
                    val = read_user_variable(key, val)

                cookiecutter_dict[key] = val
        except UndefinedError as err:
            msg = f"Unable to render variable '{key}'"
            raise UndefinedVariableInTemplate(msg, err, context) from err

    # Second pass; handle the dictionaries.
    for key, raw in context['cookiecutter'].items():
        # Skip private type dicts not to be rendered.
        if key.startswith('_') and not key.startswith('__'):
            continue

        try:
            if isinstance(raw, dict):
                # We are dealing with a dict variable
                val = render_variable(env, raw, cookiecutter_dict)

                if not no_input and not key.startswith('__'):
                    val = read_user_dict(key, val)

                cookiecutter_dict[key] = val
        except UndefinedError as err:
            msg = f"Unable to render variable '{key}'"
            raise UndefinedVariableInTemplate(msg, err, context) from err

    return cookiecutter_dict